Conventionally, 1,4-bis(aminomethyl)cyclohexane has been well known for a material for polyamides used for, for example, fiber and film. Furthermore, 1,4-bis(isocyanatomethyl)cyclohexane derived from 1,4-bis(aminomethyl)cyclohexane is useful for a material for polyurethane used for, for example, coating, adhesive, and plastic lens.
Such 1,4-bis(aminomethyl)cyclohexane includes two stereoisomers of trans-1,4-bis(aminomethyl)cyclohexane and cis-1,4-bis(aminomethyl)cyclohexane, and cis-trans isomer ratio in 1,4-bis(aminomethyl)cyclohexane affects various physical properties of polyamide and polyurethane produced by using these.
For example, in polyamide, a higher trans isomer ratio in the material 1,4-bis(aminomethyl)cyclohexane would improve physical properties such as melting point and thermal stability, and allows for production of suitable polyamide for, for example, fiber and films.
Furthermore, in polyurethane, use of 1,4-bis(isocyanatomethyl)cyclohexane derived from 1,4-bis(aminomethyl)cyclohexane having a high trans isomer ratio as the material allows for production of polyurethane with excellent heat resistance and solubility to solvents.
Therefore, improvement in trans isomer ratio in 1,4-bis(aminomethyl)cyclohexane in various industrial fields has been examined.
For example, Patent Document 1 has proposed a method for isomerization of cyclohexanebis(methylamine). In the method, to 5.0 g of 1,4-bis(aminomethyl)cyclohexane (in the following, may also be referred to as 1,4-cyclohexanebis(methylamine)) having a trans:cis ratio of 0.5:1, 0.3 g of sodium amide and 0.2 g of para-XDA are added, and the mixture is heated at 110° C. for 5 hours (see Patent Document 1 below).
In such an isomerization method of cyclohexanebis(methylamine), 1,4-cyclohexanebis(methylamine) is isomerized to achieve a trans:cis ratio of 1:1.